This is a maybe reply, maybe not. It largely depends on what you want to use the contents for - for personal use or within a company, it's probably okay (as long as you are not a multi-national and I suspect not as you would have lawyers to advise you. Often there are statements and even blocks if the copyright owner doesn't want you to use them so go to the terms and conditions of the wen site and have a look there. There may be a contact link associated with it.
4 - How long is a piece of string? You need writing experience to do this. Start with defining what you want to go into the newsletter - is it results, projects, people's backgrounds, interviews and opinions, fun parts.....and then you need to wrap over the style/atmosphere and brand of the company before even thinking about writing one word. Are you writing it or editing folk's articles? I have done both - and usually it's a mix if you go the editing route.....
For a good newsletter, it maybe better to employ someone from outside. If not a big company, this doesn't have to be a full time employee, rather someone like me - that person can also help you develop marketing communications and should ideally have a marketing sales background to get the target audience and pitch of the writing right.....if your products are scientific - good luck. We folk who can understand science/engineering and extract the benefits (and negative points to counter PR-wise) are a rare breed.